A load measuring apparatus for preventing an overload and for grasping production amount in a field and others is mounted in a dump truck that operates in a mine, a quarry and others. This load measuring apparatus measures a load on the basis of pressure applied to plural (normally, total four in the front-right, the front-left, the rear-right, the rear-left of a vehicle body) suspensions that support the vehicle body, the load measuring apparatus records and displays measured values at any time as disclosed in the following patent literature 1, for example.
In such a load measuring apparatus, it greatly depends upon a traveling path whether a state suitable for measuring a load is acquired in normal loaded traveling or not. For example, in a case seen in a quarry by cutting through a mountain that crushed stone is loaded on the upside of the mountain and a dump truck descends on a slope as it is, precise load measurement cannot be made because a traveling road has no flat location. Therefore, in the following patent literature 2, for example, a device that measures a load and records a measured value at timing hardly having the effect of a traveling state and a state of the ground, for example, during backward travel when a dump truck discharges soils is disclosed.
Besides, as disclosed in the following patent literature 3, technique for equalizing pressure of each suspension so as to inhibit the effect of a jolt in traveling and frictional resistance of suspension cylinders is also proposed. Further, as disclosed in the following patent literature 4, as lateral balance is often lost when the dump truck travels on a curved path, technique that enhances measurement precision by inhibiting load measurement in such a case is also proposed.